N-alkylhydroquinone antistain agents



2,728,65 N-ALKYLHYDROQUINONE IS TAIN S Anthony Loria, John R. Think, andArnold Weissberger, Rochester, N. Y., assignors to Eastman Kod'akCoinpuny, Rochester, N. Y., a corporation of New Jersey No Drawing.Application June 3, 1953, p

Serial No. 359,422

This invention relates to color photography'and par. ticularly to amethod for preventing the formationi of color fog or stain inphotographic emulsions.

The'method of color photography in which color-- forming or couplercompounds co'rnbine with the development product of aromatic aminophotographic deni d aw atsfl o 2,728,659 Fratented Dec. 27, 1955 ice 'layer in which they are incorporated. A further object velopers toproduce dyes is Well known. The color formers or couplers may be addeddirectly to the emulsion layers or may be incorporatedin the developingsolution as described in Fischer U. S. Patent 1,102,028, granted June30, 1914, or they may be incorporated-in a water-permeable medium whichis insoluble in the carrier for the-sensitive silver salt as describedin Mannes and Godowsky U. S. Patent 2,304,940, December 15,

1942, and Jelleyand Vittum U. S. Patent 2,322,027,

granted June 15, 1943.

A difficulty frequently encountered in these processes is the formationof color fog or stain. When the exposed material is developed in acolor-forming developer, dye fog is frequently formed'in the emulsionlayer. Thisis Because the developing agent has been oxidizedvto-some,

is to provide antistain agents which are non-difiusing in thephotographic layer and which are strong enough reducing agents to reactrapidly with oxidized 'color developer. A further object is-to provideantistain agents T which do not form highly colored oxidation products Vformula: I

extent by the action of the air and the oxidized developer I tends tocouple with the color-forming compound at places in the photographicmaterial where no silver image is produced. It is well known 'that inthese processes the dye should be formed only where the silver halide isreduced to metallic silver, thereby oxidizingthe developing agent to aform which'couples with the color former. Once the developing agent isoxidized, it couples immediately with the color former whether aphotographic image is present or not Aerial oxidation of the developeror oxidation by means other than the photographic image thereforeconverts the developer to a form which will immediately react with the'color former to produce acolor fog or stain. This effect is especiallynoticeable in materials having couplers incorporated in the sensitivelayer since there is'no coupler in the dewhen .the material containingthem is put through an oxidizing bath. Other objects will appear fromthe following description 'of'our invention.

These objects are accomplished by the use in an emulsion layer or otherlayer of a photographic material, especially a silver halide emulsionlayer in which a colored image is formed -by development in acolor-forming developer, of a normal alkyl hydroquinone having the where'R is a normal alkyl group having from 5 to 18 carbon atoms, e. g.,amyl, hexyl, heptyl, octyl, octadecyl, etc., and R- is hydrogen or thesame as R, and is attached to the hydroquinone in the 5 or 6 position. i

The following compounds are illustrative of those which we may use: V7 1. (|)H veloping solution to react with any' developing agent which isoxidized by the action of the'air. Fog or'stain arising from thesecauses is not readily controlled bythe same procedures used to controlsilvertog,

' The control of color fog or stain by incorporating hydroquinone orcertain of its derivatives in photographic emulsions is described inVittum and Wilder U. 8. Patent 2,360,290, granted October 10, 1944.Hydroquinones described therein include ,diamyl hydroquinone. anddio'ctyl hydroquinone.

The dialkyl hydroqu'inones availa.-- on able at that time were thedi-secondary and di tertiary hydroquinones. For example Konigsand Mai,Bert 25;

2649 .(1892) describes the preparation of 2,5-di-tertiaryamylhydroquinone by the m q qll Of hydroquinone with isoamylene.Tertiary octyl hydroquinone is describedin Niederl U. S. Patent2,008,032 and Robinson and Hester U; S. Patent 2,008,337;2,5-di-tertiary octyl hydroquinone has the structure:

H 2-'n-oety1 hydroquinone 2-n-dodecy1 hydroquinone Z-n-oetadecylhydroquinone 4. 0H

QI H:

HrC (CH r) H r 2,5-di-n-octyl hydroquinone 2,5 di-n-dodecy1 hy qcompound Iv-2-caprylylhydrbquinbne on I A 3-liter, 3-neck flask wascharged with a mixture of 220g. (2 moles) of hydroquinone, 433 g. (3moles) of n-caprylic acid, and 500 ml. of s-tetrachloroethane. The flaskwas fitted with a. gasdhlet tube extending. to the bottom. of the flask,a thermometer, and a gas-outlet tube to the hood, and was counterpoisedon a balance pan. Gaseous boron trifluor'ide from a cylinder was thenpassed directly into the slurry. A yellow color developed and thetemperature rose markedly; the rate of addition was regulated to keepthe temperature at 50-55" C. without external cooling. The addition wascontinued until 250 g. (3.7 moles) of boron trifluoride had beenabsorbed; about three hours was required. The flask should occasionallybe swirled by handduring the addition. The reaction mixture graduallyformed a deep-yellow solution, from which. a yellow solid separatedtowards the end of the addition. When the absorption was complete, theinlet and outlet tubes were replaced by solid stoppers and thethermometer by an air-condenser protected by a Drierite tube. Theflaskwas left standing overnight (16-20 hours) at room temperature.

The next morning, the flask was heated on a steam bath for 5-6 hours.After a short time, the mixture, which sets to an orange-yellow mushovernight, formed a deep, orange-red solution and drops of water wereap-- parent in the upper part of the flask. At the end of the heatingperiod the mixture was cooled to room temperature with a stream of coldwater. It was then poured, with mechanical stirring, into aroom-temperature solution of 615 g. (7.5 moles) of sodium acetate in3100 ml. of water in a 5-liter, 3-neck flask. An additional 100 ml. oftetrachloroethane was used for rinsing the reaction flask. The mixturewas'then stirred at room temperature for 30-40 minutes to complete thehydrolysis.

The organic layer was allowed to settle and the supernatantaqueous-layer removed as completely as possible by decantation withsuction. The tetrachloroethane solution was washed twice with'2-3 litersof water, by

stirring and decantation as above. Finally, about 2 liters of water wereadded and the mixture steam-distilled to remove the tetrachlo'roethatieand as much as feasible of the excess caprylic acid. About liters ofdistillate was eell'ect'ed'.

The residue was cooled to room temperature or below with a stream ofcold water; the product crystallized to a somewhat oily yellow-brownsolid. This was collected one large Buchner funnel, and sucked andpressed'fairly free of'water and most of the adhering oil. Then,withouttur'ther drying, it was washed with petroleum ether 'until'completely free or oil. About 500 ml. in portions,

was required. The crude product formed yellow crystals, M. P. 84-86 C.,with. preliminary softening at about 75 C. The crude yield was 361 g.(76.5%).

For purification, the material was recrystallized from a mixture of 4volumes of methanol and 1 volume ofwater, using 5 ml. per gram, with theaddition of Darco (absorbent carbon). The recovery was 327 g. of brightyellow crystals, M. P. 845-86 C., withv some softening at about 80 C.This amounts to a yield of 69% of the theoretical 472 g.

In a 500-ml., 3-neck flask, with standard-taper ground joints, wereplaced 23.6 g. (0.1 mole) of Z-caprylylhydroquinone and 2 g. of 10%palladium-on-charcoal catalyst. The air in. the flask was replaced bynitrogen, and 200 m1. of glacial acetic acid was added. The flask wasthen fitted with a fritted-glass gas-introduction tube extending to thebottom of the flask, a moderately highspeed (1700 R. P. M.) propeller orcentrifugal stirrer fitted with a rubber seal, and an air condenser withthe outlet connected to a glass tube dipping into a cylinder 0t "waterso that the reaction flask was under a pressure of "12 to 14 inches ofwater.

The stirrer was started and hydrogen gas from a cylinder was passed intothe reaction mixture at such a rate that the 'full pressure determinedby the depth of the outlet tube in the cylinder of water was maintainedin the flask. (A very slo'w streamof bubbles in the water cylinderindicates a safe rate. The speed of reduction may be estimated byshutting off the hydrogen at the inlet and observing ft'he rate at whichthe water rises in the exit tube due to the absorption of the hydrogenin the flask.

1 Whe'n the water no longer rises at all, the reduction may beconsideredcompl'ete.) The reaction was usually allowed 'to run overnight(about 20 hours), but some exper njients have indicated that 8 to '12hours might be sufficient.

Thecatalyst was removed by gravity filtration, and the flask and filterrinsed with 25 ml. of glacial acetic acid. The light-yellow filtrate washeated to boiling and treated with sma'll portions of zinc dust until nofurther 'decolori'z'atio'n occurred Z- 3 g.). The zinc dust was filteredoii and washed with 25 ml. of hot glacial acetic acid. The almostcolorless (very light yellow) filtrate and washings were treated with250 ml. of hot Water, mixed thoroughly, and cooled to 0 C. The atflrstoily precipitate soon crystallizes to a white solid. This was collectedon a Buchner funnel, washed thoroughly with water, and dried in a vacuumdesiccator. The product still contained a small amount of oilyimpetroleum ether, filtering, and washing on the funnel with 50 ml. ofpetroleum ether in portions.

The 2-n-octylhydroquinone formed a slightly oft-white crystallinepowder, M. P. 96.598 C., with some prespasms Compound4.2-caprylyl-5-nbctylhydroziuizipna CHM/ Hmon A one-liter, ,3-neckedflask was charged with a mixture of 111 g. (0.5 mole) of2-n-octylhydroquinone, 108 g. (0.75 mole) of n-caprylic acid and 250 ml.of s-tetrachloroethane. The flask was fitted with a gas inlet tubeextending to the bottom of the flask, a thermometer, and gas outlet tubeto the hood. The whole apparatus was counterpoised on a balance pan.Boron trifluoride from a cylinder is passed directly into the slurry atsuch a rate that the temperature was maintained at 40-45 C.-Considerable heat was evolved and the n-octylhydroquinone slowlydissolved to form a dark, yellow-brown solution: When about 62 g.(0.9'mole) of boron trifluoride had been absorbed which required about1% hours, the additionwas stopped; The outlet and inlet tubes werereplaced by solid stoppers and the thermometer by an air condenserprotected by a Drierite tube, and the flask left at room temperatureovernight (16-20 hours).

The flask was then heated on the steam bath for 6 hours. The mixturesoon became turbid and drops of water-were apparentin the upper partofthe flask. At the end of the heating period the mixture was cooled toroom temperature and poured, with stirring, into a room temperaturesolution of 140 g. (1.7 moles) of sodium acetate in 1260 ml. of water.An additional 50 ml. of s-tetrachloroethane was used for rinsing out thereaction flask. The mixture was stirred at room temperature for about 30minutes to complete the hydrolysis.

The organic layer was allowed to settle and was separated; the aqueouslayer was extracted in a separatory funnel with two SOO-ml. portions ofether.- The ether extracts andthe tetrachloroethane solution werecombined, washed once with 250 ml. of water and then with four 250-ml.portions of 5% sodium carbonate'solution. The; at-first dark,yellow-brown solution became lightye'llow on treatment with thecarbonate. It was finally washed with 500 ml. of water and driedovernight o'ver magnesium sulfate.

The filtered solution was concentrated under reduced pressure on thesteam bath to a volume of about 300 ml. 600 ml. of petroleum ether wasadded' and the mixture cooled to C. The precipitate was filtered off,washed free-of dark, oily material with petroleum ether, and dried inthe air. -It formed yellow crystals, M. P. 82-83" C., with somepreliminary softening at 79 C. Weight: 115 g.

- =A second cropwas obtained by concentrating the combined filtrate andwashings under reduced pressure on the steam bath to complete removal ofthe solvents. The dark oily residue was treated with 300 ml. ofpetroleum ether and left overnight in the ice box. Thev solid wasfiltered off and washed with petroleum ether to give 13 g. of yellowcrystals, M. -P. 8l82 C., softening at 77 C.

The combined crops (128 g.) were recrystallized. from 640 ml. ofcyclohexane, cooling the filtered solution overnight'at about C. Theprecipitate wasfiltered off, washed with a little cold cyclohexane andthen with three 100' ml. portions of petroleum ether. After drying'inthe. air, the product formed light-yellow crystals, M. P.

:6 82-83 C. with slight softening'at' C. 1 Yield: {122 g. (70% ofthetheoretical 174 g.)'.-] i 154.

t as

In a 3-liter, 3-necked flask with standard-taper ground I joints wereplaced 69.6 g. (0.2 mole) of, 2 -caprylyl-5- n- The stirrer was startedandhydrogen gas from a cylv inderwas passed into the reaction mixture.at such a rate that the full pressure determined by the depth of theoutlet" tube in the water cylinder was maintained in the flask. (Averyslow stream of bubbles in the watercylinder indicates a safe rate.Thespeed of reduction may be estimated by shutting off the hydrogen atthe inlet and observing the rate at which the water rises in the exittube due to absorption of hydrogen in the flask. When the water nolonger rises at all, the reduction may be considered complete.) Aperiodof 20 to 22 hours was required; this mayconveniently be overnight.Toward the end of the reaction, a bulky white precipitate formed in theflask.

When the reaction was complete, the reaction flask was warmed on thesteam bathto' 50 C.60". C.,'with continued stirring and hydrogenintroductiomnntil the white precipitate redissolved. Excessiveor..prolongcd heating should. be avoided; The catalyst was filtered offby gravity and washed with ml. of hot glacial acetic acid. The initialfiltrate was colorless, but some yellow color developed toward the endof the filtration and during the washing. The light-yellow filtrate andwashings were heated on the steam 'bath and treated with small portionsof zinc dust until no further decolorization resulted. About .5 g.,wasused, .fljhe z inc dusf'was then removed by filtration and washedwith'ja little hot'glacial acetic acid. W 1

The almost colorless filtrate was treated slowly, with stirring, with 1liter of hot water. A white precipitate formed. The mixture is cooled toabout 10 C. The precipitate was filtered oil and washed thoroughly-withwater. After drying in a vacuum desiccator at room temperature, itformed a very-slightly elf-white powder}, M. P. 80, l04-l09 C. The'weight was 66 g. i

Recrystallization from 660 ml. ofcyclohexaneffollowed by washing with 25ml. of cold cyclohexane and three IOU-ml. portions of petroleum ether,yielded 60 g. (9.0%) of white plates, M. P. 109.5 --11Ct.5 C.', withsonie pre liminary softening at l0 6 C.

Compound 6.2 caprylyl-4-rtlethoryph f l Boron trifluoride was passedinto a mixture of 124g.

(1 mole) of p-methoxyphenol, 216. g. (1.5 moles) of caprylic acid, and300 cc. of dry tetrachloroethane for -a of about four hours. Thereaction mixture was allowed to stand overnight-at room temperature andwas then heated on asteam bath for about .threehours. When cool, themixture was poured into 130 .g. of sodium acetate Three portions of2-caprylyl-4-methoxyphenol, totalling 170 g., were hydrogenated usingfor each approximately 170 cc. of glacial acetic acid, 10-12 g. of 10%palladium on charcoal, and hydrogen at 30-40 p. s. i. The reductionwasiper'form'ed in a Parr hydrogenation appararusanoomit mper mre andwas complete overnight. 2

The catalys't wa's filtered off and the filtrate poured into a largevolume of water. The organic material was extracted into ether, and't'he ether layer was neutralized with sodium bicarbonate, washed withwater, dried over sodium sulfate, and concentrated. The 4-rnethoxy-2-n-octylphenol wascollected at 187-190/ 10 mm. (yield 141 g3, 88%).

Eighty grams (0.339 mole) of 4-methoxy-2-n-octylphenol, and 65 grams(0.45 mole) of caprylica'cid were dissolved in 150cc. of'drytetrachloroethane, and boron trifiuoride was passed in for about 6hours. The mixture was heated on a-stea'm 'bath for about hours'an'dthen, 'on cooling, was poured into a large quantity of water and treatedwithexcess'sodiuin carbonate. Ether was addedto aid separation and thenthe ether layer was washed thoroughly withwater. Th'e'eth'ereal solutionwas concentrated, and the forerun removed up to B. P. 24071-0 mm. Theproduct (79g; 64%) was collected atl95-205/1 mm. Crystallizationfrom 95%alcohol gave 52.5 g. (42.5%),M. P. 30-31".

2,6-di-n-octyl-4-methoxyphenoi Three portions totalling 167 g. (0.461mole) of 2- caprylyl- 4-methoxy-E-n-octylphenol were reducedcatalytically'in a Parr hydrogenation apparatus. Each portion wasdissolved in about '250 cc. of glacial acetic acid and usedapproximately l5 .g. of 10% palladium on charcoal with hydrogen at -40lbs. per'sq. in. Reduction occurred quite slowly (ca. '20 hours) andgentle warm- Recrystallimg was required. After filtering off catalyst,the filtrate was poured into a large quantity of water and extractedwith ether. The ether extract was neutralized with sodiumca'rbonate,washed with water,dried over sodium sulfate and concentrated. 2,6 -di -noctyl 4 methoxyphenol was collected at 19o-200/1 (yield 142 'g.; 88.5%;P. 39-41 2,6-di-n-0ctylhydroquinone Twenty-five grams :of2,6-di-n-octyl-4-methoxyphenol was hydrolyzed by refluxing in a mixtureof 400 cc. of glacial acetic acid andso cc. of hydrobromic acidf(48%)for approximately 24 hours. When cool, the-reaction mixturewas pouredinto at least twice its volume of water and chilled under running waterfor a few hours. The solid was filtered off and the sticky material wasslurried carefully in thefunnel with ice-cold petroleum ether, most ofthe color and stickiness beingremoved by this proceduref The product wasrecrystallized from a mixture of approximatelyZlS cc. of ligroin (B. P.90-l20) and 215 cc. of low boiling petroleum ether, giving 15.5 g.(64%).M. P. 81.5-82.5.

v The 2,6-di n-octylhydroquinone can also be prepared as follows:

4-"rzitr0-'2,6-di-n-octylphenol In a 200-ml. flask were mixed 5.64 g.(0.02 mole) of 10-nona'tlecanone"(5.-A. -C. S., 55, 1697), 2.5 g. (0.02mole) sodium nitromalonaldehyde (Amer. Chem. 1., 22, 4), ml. of absoluteethyl alcohol, and 5 g. of potassium hydroxide dissolved in 40 ml. ofwater. The flask was equipped with a water-cooled condenser and themixture refluxed on a steam bath for 18 hours. The reaction mixture wascooled to about 20 C. and the small amount of colorless precipitate thatformed was filtered and washed on the funnel with 25 ml. of cold water.The filtrate and the wash water were combined and evaporated to about 50ml. and let stand overnight. The yellow crystalline precipitate thatformed was filtered and washed on the funnel 'with 25 ml. of ice-coldwater. It was suspended in ml. of 50 percent aqueous alcohol andacidified with 4 ml. of dilute hydrochloric acid. The colorless solidthat formed was collected and crystallized twice from acetonitrile.There was obtained 4.1 g. of product melting at 75-76" C.

' 2,6-di-n-octylquinone The 4-nitro-2,6-di-n-octylphenol was reduced tothe amino compound using Raney nickel catalyst and 10 ml. of 30 percentsodium dichromate in water was added dropwise to an aqueous acetonesolution of the 2,6-di-noctyl-4-aminophenol (2.2 g. in 100 ml. ofacetone+50 ml. of water) at room temperature with mechanical stirring.After 3 hours, the acetone was evaporated under reduced pressure, andwater was added to the residue. The oily yellow solid formed was takenup in ether; the ether solution was washed with water, dried over sodiumsulfate, and the solvent evaporated. The yellow solid residue melted at57-60 C.

2 ,6 -di-n-o'cly lhydroquin one An acetic acid solution of2,6-di-n-octylquinone (2.2 g. in 50ml.) was heated to reflux and whilestirring 3 g. of zinc dust was added to it. in small portions. After 30minutes refluxing, the excess zinc was removed by filtration, and thefiltrate was added to 200 ml. of cold water. The mixture was allowed tostand overnight; the precipitate that formed was filtered, washed wellwith water, and air-dried. The dried product was crystallized threetimes from petroleum ether, B. P. 30-60 C. There was thus obtained awhite crystalline solid melting at 8283, which, on'standing, turns to apink color.

Compound 25+2-n-d0decylhydr0quin0ne Z-n-rlodecylhydroquinone (M. P.l06.5108 C.) was prepared as described by Cook, Heilbron, and Lewis, J.Chem. Soc., 1942, 659, with certain modifications, e. g., reduction ofthe intermediateketone with palladiumon-charcoal catalyst.

Compound "3.-.2-n 0ctadecylhydroquirione 2-n-octadecylhydroquinone (M.P. 114-115 C.) was prepared as described by Cook, Heilbron, and Lewis,J. Chem. Soc., 1942, 65 9., reducing the intermediate ketone, however,with palladium-on-charcoal catalyst.

' Compound 5 .-2,5 -di-n-d0decylhydroquinone Patent 2,423,730, whenincorporated in this way, produce dyes upon color development which areprone to fading by the action of visible or ultraviolet light, whenknown antistain agents such as 2,5-di-tert. octyl hydroquinone are usedin the emulsion layer. These are the yellow and cyan dyes. The magentadyes, such as those formed from couplers described inLoria, Weissbergerand Vittum U. S. Patent 2,600,788 are relatively little affected by theknown antistain agents upon the action of light.

In order to illustrate the effect of our antistain agents, the followingtest was made.

A quantity of the antistain agent, the molar equivalent of 0.05 g. of2,5-di-tert. octyl hydroquinone, was dissolved with 0.5 g. of coupler in1.5 cc. of dibutylphthalate. To this solution was added 11 cc. of 10%gelatin solution and 2.8 cc. of Alkanol B (sodium alkyl naphthalenesulfonate) solution. The mixture was passed through a colloid mill threetimes, and to the resulting dispersion, 32 cc. of a gelatino-silverhalide emulsion were added, and the mixture blended and coated on a filmsupport so'that the anti-stain agent was equivalent to 5 mg. per sq. ft.of 2,5-di-tert.-octyl hydroquinone.

Two check coatings were made: one containing no anti-stain agent, andone containing 5 mg. per sq. ft. of 2,5-di-tert. octyl hydroquinone.

The film strips were exposed on a Ib sensitometer using a silver wedgevarying in density from 0 to 3. They were then developed 10 minutes at68 F. in the following developer:

G. 2-amin05-diethylamino toluene HCl ,2 Sodium sulfite (desiccated) 2Sodium carbonate, monohydrate Potassium bromide 2 Water to 1 liter.

This was followed by 5 minutes in the following stop bath:

Sodium sulfite, desiccated g 75 Acetic acid (28%) 235 Boric acid,crystals 3 37.5 Potassium alum g 75 Water to 1 liter.

Loss in density at maximum absorption Cyan Yellow Agent dye dye Cheek(none) 0 0 2 5-di-tert. octylhydroquinone- .08 poun 01 10 .06 10 .09 .04.08 +.01

These results show that in the case of the cyan dye, all of the agentscaused less fading than 2,5-di-tert. octyl hydroquinone. ,In the case ofthe yellow dye, compounds 1, 3 and 6 showed an increase in density overthe standard, and compound 4 produced about half as much loss in densityas the standard.

T he antistain agents of our invention may also be used in non-sensitiveovercoating or filter layers, such as a colloidal silver interlayer ofmultilayer photographic material. In general, the antistain agents ofour invention are used in the emulsion or other layer in quantitiesranging from 0.07 gram to 4.3 grams per liter of emulsion or gelatinsolution. These values are, however, merely illustrative.

In certain cases the antistain agents of our invention.

may be incorporated in a processing solution such as a prebath, firstdeveloper bath,.or color-forming developer used with color film which isdeveloped with a primary aromatic aminodeveloping agent.

Our materials are particularly useful with color-forming emulsionscoated on paper supports where it is especially important to reduce theminimum or fog densities. This applies both to negative developed paperand to reversal paper as well as to transparency materials.

It will be understood that the examples and modifications describedherein are illustrative only and that our invention is' to be taken aslimited only by the scope of the appended claim.

We claim:

A color-forming photographic emulsion having reduced fogging tendency,comprising a silver halide emulsion having incorporated therein anon-diffusing coupler compound capable of coupling with the oxidationproduct of a primary aromatic amino developing agent and as an where Rand R are normal alkyl groups of from 9 to 18 "carbon atoms, and R isattached to the hydroquinone nucleous in a position selected from theclass consisting of 5 and 6 positions.

References Cited in the file of this patent UNITED STATES PATENTS2,360,290 Vittum et a1. Oct. 10, 1944

